The present invention relates to a silver halide photographic material, particularly to a silver halide photographic material that is improved in color forming ability, storage stability of dye image and film properties.
The most common method of forming dye images with silver halide color photographic materials is to form dyes by the reaction between photographic couplers and the oxidation product of color developing agents. For ordinary color reproduction, magenta, yellow and cyan couplers are used as photographic couplers, and aromatic primary amino color developing agents are used as color developing agents to form azomethine dyes, indoaniline dyes and other dyes. The couplers described above are usually incorporated in separate light-sensitive layers in superposition. Besides these light-sensitive layers, non-light-sensitive layers and protective layers also contain anti-color mixing agents, ultraviolet (uv) absorbers and other additives with a view to improving the quality of image and the storage stability of dye image.
Thus, many additives are incorporated in silver halide photographic materials in order to have silver halides exhibit their characteristics to the fullest extent. The additives incorporated in silver halide photographic materials are versatile in water solubility and range from water-soluble to water-insoluble compounds. Examples of "hydrophobic" compounds which are insoluble or slightly soluble in water include dye image forming couplers, ultraviolet absorbers, antifading agents, anti-color mixing agents, redox compounds and anti-foggants. In order to incorporate these hydrophobic compounds into hydrophilic colloidal layers, they must be finely dispersed to form an emulsion of an oil-in-water or "oil protected" type. While several methods have been proposed to disperse hydrophobic compounds, one approach is to disperse them in the presence of surfactants together with organic solvents such as dibutyl phthalate and tricresyl phosphate, as described in U.S. Pat. Nos. 2,322,027, 2,835,579, 3,748,141, JP-B-54-24288 (the term "JP-B" as used herein means an "examined Japanese patent publication") and JP-A-56-114940 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), and another approach is to disperse hydrophobic compounds together with polymer compounds, as described in U.S. Pat. Nos. 2,772,163, 2,852,382 and JP-A-51-25133.
These methods, however, have been found to be unsatisfactory in one way or another. For instance, they cause deterioration in color forming ability and lightfastness. Even if these problems can be avoided, dye images, when stored in a humid condition, will deteriorate in the gloss of film surface. The deterioration in color forming ability has been particularly great when developers that do not contain benzyl alcohol are used. As for the method that disperses hydrophobic compounds together with polymer compounds, the deterioration of color forming ability can be prevented to some extent by increasing the proportion of hydrophilic monomers such as acrylic acid but the improvement is still insufficient to produce completely satisfactory light-sensitive materials.
JP-A-63-44658 describes an invention that intends to improve the storage stability of image by dispersing a specific dye image forming coupler together with a polymer compound in the absence of a high-boiling point organic solvent. This methods is effective to some extent in improving the storage stability of image but on the other hand, it causes a substantial deterioration in color forming ability.